Obstructed View Factor Calculations for Multiple Obstructions in Closed Cavities

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
Fiaz Mahmood ◽  
Huasi Hu
Keyword(s):  
Inertial Confinement Fusion ◽  
Surface Element ◽  
View Factor ◽  
Inertial Confinement ◽  
X Rays ◽  
Confinement Fusion ◽  
Indirect Drive ◽  
Fortran 90 ◽  
Summation Rule ◽  
Effect Method

The inertial confinement fusion (ICF) program has been mainly concentrating on the indirect drive approach for the last three decades, due to relaxed requirements on driver-beam uniformity and reduced sensitivity to hydrodynamic instabilities. The optimal designs are important for maximum conversion of driving energy to X-rays, and finally, symmetrical irradiation of the capsule. The view factor (VF) evaluation is an important parameter providing significant radiation heat transport information in specific geometries. The present study is aimed at the VF calculations for closed cavities. The VF calculations include the case of energy transfer from one infinitesimal surface element of the enclosure to other similar infinitesimal surface elements of the cavity. Similarly, the obstructed VF is also calculated when multiple obstructions are present in the cavity. Two distinct computer programs are developed by programming in FORTRAN-90 to evaluate unobstructed VF and obstructed VF for a square geometry. The calculations are based on the crossed strings method, which is more reliable for simple geometries. The shadow effect method is used for the obstructed VF calculations. The results of the developed programs are benchmarked using the summation rule. In the case of no obstacles in the cavity, VF calculations solely obey the summation rule. However, in the presence of obstacles in the cavity, obstructed VF calculations showed the acceptable difference in comparison with the summation rule.

scholarly journals Demonstration of symcaps to measure implosion symmetry in the foot of the NIF scale 0.7 hohlraums

2009 ◽  
Vol 27 (1) ◽  
pp. 123-127 ◽  
Author(s):  
A. Seifter ◽  
G.A. Kyrala ◽  
S.R. Goldman ◽  
N.M. Hoffman ◽  
J.L. Kline ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Inertial Confinement ◽  
X Rays ◽  
X Ray ◽  
Precise Control ◽  
Confinement Fusion ◽  
Laser Facility ◽  
Drive Pulse ◽  
Indirect Drive ◽  
Omega Laser

AbstractImplosions using inertial confinement fusion must be highly symmetric to achieve ignition on the National Ignition Facility. This requires precise control of the drive symmetry from the radiation incident on the ignition capsule. For indirect drive implosions, low mode residual perturbations in the drive are generated by the laser-heated hohlraum geometry. To diagnose the drive symmetry, previous experiments used simulated capsules by which the self-emission X-rays from gas in the center of the capsule during the implosion are used to infer the shape of the drive. However, those experiments used hohlraum radiation temperatures higher than 200 eV (Hauer et al., 1995; Murphy et al., 1998a, 1998b) with small NOVA scale hohlraums under which conditions the symcaps produced large X-ray signals. At the foot of the NIF ignition pulse, where controlling the symmetry has been shown to be crucial for obtaining a symmetric implosion (Clark et al., 2008), the radiation drive is much smaller, reducing the X-ray emission from the imploded capsule. For the first time, the feasibility of using symcaps to diagnose the radiation drive for low radiation temperatures, <120 eV and large 0.7 linear scales NIF Rev3.1 (Haan et al., 2008) vacuum hohlraums is demonstrated. Here we used experiments at the Omega laser facility to demonstrate and develop the symcap technique for tuning the symmetry of the NIF ignition capsule in the foot of the drive pulse.

scholarly journals Influence of Au M-band flux asymmetry on implosion symmetry

2017 ◽  
Vol 35 (2) ◽  
pp. 337-343
Author(s):  
S. Jiang ◽  
L. Li ◽  
L. Jing ◽  
L. Kuang ◽  
H. Li ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Three Dimensional ◽  
View Factor ◽  
Inertial Confinement ◽  
Confinement Fusion ◽  
Laser Facility ◽  
Indirect Drive ◽  
Si Doped ◽  
The Asymmetry ◽  
Factor Code

AbstractIn indirect-drive inertial confinement fusion, the radiation symmetry must be controlled for the achievement of hotspot ignition. The radiation symmetry is of great importance. In this paper, we investigate the drive asymmetry of the M-band (2–5 keV) radiation emitted from an Au holhraum wall by using the three-dimensional view-factor code IRAD3D. Analysis of the M-band flux drive at the Shenguang-III laser facility shows that it is asymmetric and that the asymmetry varies with time. For a given cross section over the pole, the initial M-band flux asymmetries are P2 = 11.59, P4 = 1.41, and P6 = −0.64%. When the asymmetries are artificially added to a symmetric radiation drive, the position of the deuterium-tritium (DT) ice/gas interface is asymmetric for a National Ignition Facility capsule in 1D simulation. This means that M-band flux asymmetry can lead to implosion asymmetry even if the total radiation is symmetric. Pure CH and Si-doped CH capsules are considered. The results show that a mid-Z dopant can partly reduce the asymmetry. However, the asymmetry is still very large. Thus, it is necessary to study the M-band flux asymmetry and its influence on the implosion symmetry.

scholarly journals Pulsed power indirect drive approach to inertial confinement fusion

2020 ◽  
Vol 36 ◽  
pp. 100749 ◽  
Author(s):  
R.E. Olson ◽  
R.J. Leeper ◽  
S.H. Batha ◽  
R.R. Peterson ◽  
P.A. Bradley ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Pulsed Power ◽  
Inertial Confinement ◽  
Confinement Fusion ◽  
Indirect Drive

W and B4C Coatings for Nuclear Fusion Reactors

1998 ◽  
Author(s):  
A. Cavasin ◽  
T. Brzezinski ◽  
S. Grenier ◽  
M. Smagorinski ◽  
P. Tsantrizos
Keyword(s):  
Inertial Confinement Fusion ◽  
Nuclear Fusion ◽  
Energy Levels ◽  
High Hardness ◽  
Fusion Reactors ◽  
Inertial Confinement ◽  
X Rays ◽  
First Wall ◽  
Term Operation ◽  
Confinement Fusion

Abstract The development of nuclear fusion reactors is presently considered to be the only possible answer to the world's increasing demand for energy, while respecting the environment. Nuclear fusion devices may be broadly divided into two main groups with distinctively different characteristics: magnetic confinement fusion (MCF) and inertial confinement fusion (ICF) reactors. Although the two nuclear fusion technologies show similarities in energy levels (as high as 3 J/cm2) and type of environment (high temperature plasmas) to be contained, the materials of choice for the protective shields (first wall in the ICF and deflectors in the MCF) differ significantly. In ICF reactors, multiple laser beams are used to ignite the fuel in single pulses. This process exposes the first wall to microshrapnel, unconverted light, x-rays, and neutrons. B4C is a low Z material that offers high depth x-ray absorption to minimize surface heating, is not activated by neutrons (will not become radioactive), and offers high hardness and vapour temperature. The long term operation envisioned within MCF reactors, where a continuous nuclear fusion of the fuel is sustained within the confinement of a magnetic field, favours the use of high Z materials, such as W, to protect the plasma exposed deflectors. The reason is a lower erosion rate and a shorter ionization distance in the plasma, which favours the redeposition of the sputtered atoms, both resulting in a lower contamination of the plasma. The production of the first wall and the deflector shields using solid B,C and W materials respectively, is obviously unthinkable. However, ProTeC has developed high density coatings for both ICF and MCF nuclear fusion reactors. W coatings with less then 2% porosity have been produced for both, the Tokamac MCF reactor and its Toroid Fueler. The toroid fueler is a plasma generating device designed to accelerate particles and inject them into the centre of the operating fusion reactor in order to refuel. For the application in an ICF reactor, B4C coatings exhibiting porosity levels below 3% with a hardness above 2500 HV have been deposited directly onto Al substrate. Properties such as outgassing, resistance to erosion and shrapnel, and the influence of x-rays have been studied and showed exceptional results.

Application of view-factor method on indirect inertial confinement fusion

2010 ◽  
Vol 22 (5) ◽  
pp. 1053-1058
Author(s):  
周近宇 Zhou Jinyu ◽  
黄天晅 Huang Tianxuan ◽  
蒙林 Meng Lin ◽  
蒋炜 Jiang Wei ◽  
黎航 Li Hang ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
View Factor ◽  
Inertial Confinement ◽  
Factor Method ◽  
Confinement Fusion

scholarly journals Experimental investigation of Z-pinch radiation source for indirect drive inertial confinement fusion

2019 ◽  
Vol 4 (4) ◽  
pp. 046201 ◽  
Author(s):  
Zhenghong Li ◽  
Zhen Wang ◽  
Rongkun Xu ◽  
Jianlun Yang ◽  
Fan Ye ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Radiation Source ◽  
Inertial Confinement Fusion ◽  
Inertial Confinement ◽  
Confinement Fusion ◽  
Indirect Drive ◽  
Z Pinch

Indirect-Drive Inertial Confinement Fusion Using Highly Supersonic, Radiatively Cooled, Plasma Slugs

2002 ◽  
Vol 88 (23) ◽  
Author(s):  
J. P. Chittenden ◽  
M. Dunne ◽  
M. Zepf ◽  
S. V. Lebedev ◽  
A. Ciardi ◽  
...  
Keyword(s):  
Inertial Confinement Fusion ◽  
Inertial Confinement ◽  
Confinement Fusion ◽  
Indirect Drive
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